A statistical examination of wealth inequality within the Forbes 400 richest families in the United States from 2000 to 2023

Between 1989 and 2019 the wealth of the Forbes 400 grew four times as fast as that of the median household and twice the rate of a family at the 95th percentile, demonstrating a substantial imbalance in the growth of financial assets between the super-rich and the general population. A natural question is: how similar are the results of analyzing wealth data, especially data pertaining to the very rich, using different measures of inequality? This paper compares the rates of growth of wealth inequality within the Forbes 400 using the Gini, Bonferroni, De Vergottini, Theil, Mean log deviation measures and a median-based version of the Gini index to explore inequality within the Forbes 400. While all indices decreased from 2000 until 2008 and increased subsequently, indices giving greater weight to the upper end increased more rapidly. Because the Forbes 400 possess substantial assets, their wealth responds faster to major events affecting the economy, e.g. the dot-com boom of 1999–2000, the 2008 recession and the recent pandemic. The inequality within the Forbes 400 and that of the general population were essentially uncorrelated during the period studied, implying that changes in the economic status of the “super-rich” and general population follow different patterns.